Device for the Elastic Foreshortening of Cable, Rope or other Flexible Linear Structures

ABSTRACT

Improvements to a device as previously disclosed in U.S. Pat. No. 7,219,397 wherein an elastic cord is attached to a pre-existing flexible linear structure such as a wire, tube, or rope to deform the structure and impart elastic handling properties. The improvements include features necessary for the effective manufacture and use of the device.

CROSS REFERENCE TO RELATED APPLICATIONS

U.S. Pat. No. 7,219,397 B2

FEDERALLY SPONSERED RESEARCH

Not applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of Invention

The Curly Cord retractile arrangement is common on all types of linear structures including leashes and tubing, but most commonly the telephone hand-set. It has the function of making the cord more convenient and functional. The inventor was awarded the abovementioned US patent for a retrofit device that imparts retractile properties to formerly non-retractile cords. This submission teaches novel and important features that are required to perfect the invention for the marketplace and for manufacturing.

2. Prior Art

The current application builds on the invention of U.S. Pat. No. 7,219,397 B2 Dated May 22, 2007 issued to the inventor, Todd N Bishop.

Since issuance, the inventor has diligently pursued reduction to practice, including experimenting with numerable embodiments and specific arrangements within the limits of the patent application. Some of these refinements constitute significant improvements both functionally and from a commercial standpoint such that the inventor has decided that additional patent coverage is important to the commercial success of the invention. So much so, that he believes that it would be difficult or impossible for a competitor to create a successful product based on the original patent without these improvements.

SUMMARY

This case will address:

-   -   1. Two novel arrangements of the knots to allow the most         possible loops with the shortest possible pre-assembled length.     -   2. A feature in the former tube that prevents premature release         of the first several knots onto the linear structure during         application.     -   3. Stiffening of one end of the former tube to facilitate         crushing the tube into a frustum of a cone to improve dispensing         of the knots and handling during installation.     -   4. A loop of the elastic cord formed at one end of the assembly         of the elastic with a linear structure to bind a connecting         linear structure and eliminate disconnecting of the cords during         use.     -   5. A means to secure the elastic cord to the former tube during         manufacturing that is critical to continuous manufacturing of         the invention.     -   6. A relief groove in the exterior of a support structure to         facilitate clearance between the support and surfaces on the         means to secure the cord to the former tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 describes the preferred embodiment including the elastic cord 1 with slippable knots 2 and encircling loops 3, positioned on a former tube 4 structure having a stiffened 5 and non-stiffened 6 end, and having a securing means 7 through the material of the former tube 4 to secure the cord 1 for manufacturing purposes. The former tube 4 is also comprised of a feature 8 in the material of the tube positioned so that it catches a loop 3 of the elastic cord 1 as it is being displaced off of the former tube 4, so that each of the successive knots 2 are fully tightened before the next knot 2 is distributed off of the former tube 4. An internal support tube 9 that supports former tube 4 that, in turn, supports the stretched elastic loops 3 is shown removed from the former tube 9. The support tube 9 has an axial groove 10 in the exterior surface to provide clearance for the staple 7 during insertion and removal. The preferred embodiment shows of a plurality of knots 2 having a loop 3 around the former tube 4, each knot 2 being offset 12 from the adjacent knots 2 so that subsequent loops 3 can be positioned as close as possible to adjacent loops.

FIG. 2 describes a former tube 4 comprised of a plurality of knots 2 in the elastic cord 1 that are not offset 14, such that interference between surfaces of the subsequent knots 2 causes loops 3 in the elastic that encircle said former tube 4 to be held apart from each other.

FIG. 3 describes the assembly of elastic cord 1 and former tube 4 wherein loops 3 in the elastic 1 that encircle the former tube 4 are positioned on the carrier former tube 4 in a plurality of layers 13 to increase by multiples the number of knots 2 that can be positioned on the former tube 4, and ultimately deposited on the flexible linear structure 11.

FIGS. 4 a and 4 b are a closer view of the stiffened end 5 of the former tube 4 showing a staple 7 through the material of the former tube 4, securing an end of the elastic cord 1.

FIG. 5 is an arrangement of the invention wherein the loops 3 are placed in layers so that the number of loops possible on a length of former tube 4 may be two or more times that possible on a single layer arrangement.

FIG. 6 is an assembly of the elastic cord 1 onto a flexible linear structure 11 comprised of a free loop 15 at an end of the linear structure 11.

THE PREFERRED EMBODIMENT

The preferred embodiment of the referenced patent is a length of elastic cord 1 that has been formed into a plurality of slippable knots 2 around the exterior diameter of a former tube 4, having an internal diameter that is larger than the largest outside dimension of the largest feature a flexible linear structure 11, such as a connector on an electrical cord. This invention teaches a deformable former tube 4 comprised of a cylinder with one end stiffened 5 by rolling the material of the tube 4 into a bead 5 and an opposing non-stiffened 6 end. Each slippable knot 2, having at least one loop 3 around the former tube 4 such that the elastic, is a series of slippable loops 3 secured by knots 2 around the former tube 4. The knots 2 are arranged in an offset pattern 12, down the major axis of the former tube 4, such that the loops 3 can be in the closest possible proximity to the next loop. The loops 3 may be loosely positioned or tightly stretched around the structure depending on the results desired. An end of the elastic cord 7 is positioned near the non-beaded end 6 of the former tube 4.

OPERATION OF THE PREFFERED EMBODIMENT

During installation, the former tube 4 is displaced over a free end of the linear structure 11 into a position to deposit the first slippable knot 2. The former tube 4 may then be collapsed 4 a by external pressure such that the stiffened (beaded) end 5 remains as substantially the original diameter and the non-beaded end 6 is reduced to a smaller diameter so that the former tube 4 and elastic take the form of a frustum of a cone. The loops of the elastic cord 1 can then be displaced toward the smaller, non-stiffened 6 end of the former tube 4 with minimum binding. During assembly, the knots 2 are displaced off of the non-stiffened end 6 of the former tube 4 onto the flexible linear structure 11, and the elastic is stretched tightly until each slippable knot 2 tightens around the linear structure 11. Once completed, the remaining material is used to form a free loop at an end of the assembly that may be used to bind common electrical plug at the end of the assembly to an opposing feature such as the receptacle on an extension power-cord.

The flexible linear structure 11 may be a flexible wire, tube, rope, or strap in any of the variety of forms these products are available in. Once the assembly is in a starting position on the linear structure 11, an end of the elastic cord 1 is secured to a location on the linear structure 11, and the former tube 4 is displaced back along the flexible linear structure 11 such that the knots 2 are sequentially pulled off of the former tube 4 and onto the flexible linear structure 11. This causes the elastic to stretch and each of the slippable knots 2 to be tightened onto the exterior of the flexible linear structure by the displacement of the former tube 4. Once some or all of the knots 2 have been tightened onto the exterior of the linear structure 11, the assembly of the elastic and the flexible linear structure is released allowing the elastic to retract, pulling the linear structure into a foreshortened state in the form of a series of loops 3 and bends. After a knot 2 has been placed near a free end of the linear structure, the former tube 4 is displaced off of the free end of the linear structure 11. At that time, one or more additional knots 2 may be pulled off of the former tube 4. Since the former tube 4 is now off the end of the linear structure, the slippable knots 2 have nothing to tighten around, one or more slippable knots 2 will simply be pulled out and disappear. The former tube 4 may then be displaced back over the free end of the linear structure and a knot 2 displaced onto that end so that a loop of elastic cord 1 is formed at a free end of the assembly. That loop may then be used to secure the linear structure 11 to a free end of an opposing object such as a receptacle end of a common power cord

It is very important to the invention to get as many slip knots 2 as possible on the shortest former tube 4. The slip knot 2 is comprised of a plurality of smaller loops around the material of the elastic cord 1 that secures the cord 1 and the loops 3 around the former tube 4. Because it is comprised of several loops, the slippable knot 2 is necessarily larger than the elastic cord itself, normal to the primary axis of the elastic cord 1, such that contact between surfaces of the successive knots 2 causes the loops 3 around the tube 4 to be held apart around the exterior of the former tube 4 (FIG. 2). When knots 2 are aligned linearly 14, the loops 3 around the tube 4 may be more than twice as far apart as would be possible without interference. The resulting assembly must be twice as long to have the needed number of loops 3, creating difficulty in application and resulting in a bulkier and more expensive end-product. This is addressed by staggering the position of the knots 2 on the former tube 4 into an offset pattern 12 so that the knots 2 are not directly aligned. A simple helical distribution in one direction is functional, but the zigzag pattern 12 is the preferred embodiment (FIG. 1). In most cases, it is important that the loops 3 be as tight and the knots 2 be as close to each other on the former tube 4. There are applications where the assembly may be designed to space the knots 2 further apart. In this case, it would be advantageous to position the knots 2 further apart, even on opposite sides of the former tube 4 from one another so that no pattern, either helical or zigzag would result. It is understood that any arrangement of knots 2 is permissible.

Another approach to creating an even denser knot 2 pattern, and therefore a shorter more functional product, would be to lay the loops 3 in a layered pattern 13 by placing one or more successive knots 2 on top of each other such that they can still be moved off of the former tube 4 and onto the flexible linear structure 11 by the end user. This would require a much stronger former tube 4 structure, because of the multiplied crushing forces if the elastic is stretched tightly around the former tube 4. It is important when layering loops 13 to offset the knots 2 so that they are not laying on-top of one another. This is best done by offsetting knots circumferentially relative to the one beneath it.

It is difficult to pull tightened slip knots 2 off of a long former tube 4 because the slippable loops 3 that encircle the tube 4, tighten around the tube 4 as they are pulled along its axis. Our preferred embodiment is a former tube 4 having one end stiffened 5 such that the tube 4, when collapsed at the non-stiffened end 6, becomes substantially conical 4 a. In the preferred embodiment, an end of the former tube 4 is stiffened by shaping the material the tube 4 into a rolled, substantially donut-shaped bead 5, the primary axis of the bead forming a circle, normal to the axis of the former tube 4 with its center point on the primary axis of the former tube 4 (FIG. 3). Said bead does not require a round cross-section, but may be any geometric shape. The resulting increased section modulus of the bead shape substantially stiffens that end 5 of the tube 4. Other separately made means of stiffening an end of the tube 4 are envisioned such as an inter-fitting insert positioned in proximity to surfaces of the inside of the former tube 4 or an inter-fitting collar with surfaces in proximity to exterior surfaces of the former tube. The rolled end 5 also prevents elastic loops 3 from being accidentally pulled off of the stiffened end 5 during application, and it provides a sturdy feature for the user to pull during installation. The stiffened end 5 is defined as having at least 20% greater resistance to external radial crushing forces than the non-stiffened end 6.

The foreshortening effect on the linear structure 11 is dependent on the stretchiness of the elastic cord 1. Fabric covered elastic cord is the preferred cord material, but commonly available bungee or sewing elastic stretches to about twice its relaxed length before the weave of the fabric cover restricts further stretch (typically the rubber core material can stretch much more than that). The inventor has facilitated the development of elastic that stretches to three times its relaxed length giving the foreshortened assembly a much shorter foreshortened length which usually is considered more functional and more esthetic. Elastic cord 1 with more elasticity would be desirable and is anticipated.

In continuous manufacturing, it became necessary to hold the elastic to the former tube 4 so that when individual parts are cut from the feed stock, the elastic does not come loose and become lost to the process. Research determined that the most practical means was a mechanical fastener 7. The preferred embodiment includes a common staple 7, penetrating the material of the former tube 4 and bent over on the opposing side to secure it. Other means are envisioned including punching the elastic through the tube 4, glues, tapes, wraps, or a feature built into the former tube 4 or the internal support tube 9 that catches and holds the elastic once it is punched through.

Sewing elastic and bungee cords are commonly either a polyester or nylon fiber. These are inexpensive, but are relatively weak. The inventor has found it beneficial in some applications to use one of a family of aerospace reinforcements such as but not limited to, Aramid (Kevlar™ by DuPont, Twaron® or Technora® by Teijin), Liquid Crystal Polymer-LCP (Vectran™ by Kuraray), Ultra High Molecular Weight Poly Ethylene UHMWPE (Spectra™ by Honeywell or Dyneema® by DSM Corp) because of increased tensile strength and wear resistance. This is especially true in industrial applications where rough usage will prematurely destroy common polyester or nylon commercial elastic or bungee-cord.

Power cord users employ methods to assure that their cords do not come unplugged during use. The most common and the most damaging technique is to tie an overhand knot between the cords and then plug them in. This bends and puts stress on the wire to the connectors at the entry point, often resulting in fraying and failure of the conductors. The invention employs a short, free-loop of the elastic cord 1 at the free end of the assembly 15 so that when it is wrapped around a free end of the connecting cord, the loop 15 holds the cords together without contorting the ends and causing damage.

Without experience, it is common to pull more than one loop 3 off of the former tube 4 during the start of installation, causing loss of product, sloppy appearance and rework. The addition of a feature on the former tube 4 to restrain each knot 2 as it is being pulled off, reduces the problem by holding each loop 3 until the knot 2 before it is substantially tightened onto the linear structure 11 and the elastic between them is fully stretched. This results in an even distribution of knots 2 along the linear structure after assembly. The preferred embodiment utilizes a substantially circumferential saw cut 8 in the material of the former tube 4 located near the non-beaded, distribution end 6 of the former tube 4, but other means such as protrusions from the tube 4, and a restrictive coating or tape on the loops 3 is envisioned.

A support tube 9 is required on the inside of the former tube 4 prior to use to prevent premature collapse of the former tube. This can be any rigid material. We have found that the staples 7 used to secure the cord drag on this during removal and that an axial groove 10 on the outside of the support tube 9 to clear the staples is advantageous. 

1. An apparatus to foreshorten and impart axially elastic handling properties to a flexible linear structure comprised of a plurality of loops in an elastic cord that form knots binding the elastic cord around a former tube, said elastic cord comprising an external jacket woven from fiber made from materials chosen from the set of Aramid, Liquid Crystal Polymer, or Ultra High Molecular Weight Polyethylene.
 2. An apparatus to foreshorten and impart axially elastic handling properties to said flexible linear structure comprised of a plurality of loops in said elastic cord that form knots binding the elastic cord around said former tube such that the position of said adjacent knots are circumferentially offset along an axis of said former tube and inter-fitted with adjacent knots so that interference between surfaces of the knots, is substantially minimized.
 3. The apparatus of claim 2 wherein a length of elastic cord forms a loose loop at an end of the flexible linear structure having both ends of said loop affixed to the flexible linear structure.
 4. The apparatus of claim 2 wherein the elastic cord comprising at least two parallel cords.
 5. The apparatus of claim 2 wherein the series of elastic cord loops encircling the former tube are positioned in at least two layers surrounding the former tube such that an inside loop, having an inside diameter surface in contact with an outside surface of the former tube and has an outside diameter surface that is in contact with and supports a surface of an outside loop of elastic cord encircling the former structure.
 6. The apparatus of claim 2 wherein the position of a slippable knot of said inside loop of elastic cord is circumferentially offset sufficiently to reduce or eliminate contact between surfaces of a knot of said outside loop of elastic cord.
 7. An apparatus to foreshorten and impart axially elastic handling properties to a flexible linear structure comprised of a plurality of loops in an elastic cord that form knots binding the elastic cord around a former tube structure wherein said former tube comprising two ends, an end that is open and not modified and an opposing stiffened end comprising a reinforcement means.
 8. The apparatus of claim 7 wherein said stiffened end comprising the material of the former tube having been formed on the stiffened end into a generally donut shaped bead located around, and normal to a primary axis of the former tube and having a center point on said primary axis.
 9. The apparatus of claim 7 wherein surfaces of a separately constructed stiffening member are inter-fitted with and support the stiffened end of the former tube
 10. The apparatus of claim 9 wherein surfaces of the stiffening member are inter-fitted with inside surfaces of the former tube.
 11. The apparatus of claim 9 wherein surfaces of the stiffening member are inter-fitted with outside surfaces of the former tube.
 12. An apparatus to foreshorten and impart axially elastic handling properties to a flexible linear structure comprising a plurality of loops in an elastic cord that form knots each having a loop around the former tube structure where in the elastic cord is secured in at least one location to the material of the former tube by a securing means.
 13. The apparatus of claim 12 wherein said securing means is selected from the set of glue, tape, a mechanical fastener, a wrap, punching the cord through the material of the tube or melting it into the material of the former tube.
 14. The apparatus of claim 12 having a removable internal support member which is substantially cylindrical having a nominal outside diameter around the primary axis, said outside diameter being less than an internal diameter of the former tube such that said internal support member may be inserted into the former tube along its primary axis, the support tube having a substantially axially oriented segment of its outside surface that is less in diameter than the remainder of the nominal outside diameter of the internal support member. 